FXUS62 KCHS 280521
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1221 AM EST SAT NOV 28 2009
.SYNOPSIS...
HIGH PRES WILL BUILD OVER THE REGION THIS WEEKEND. A COLD FRONT WILL
MOVE THROUGH FROM THE NW MON NIGHT...THEN STALL S OF THE AREA ON
TUE. A GULF LOW PRES SYSTEM WILL DEVELOP TUE AND MOVE UP THE COAST
WED THROUGH THU...FOLLOWED BY HIGH PRES LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE MAIN CONCERN FOR OVERNIGHT CONTINUES TO BE THE POTENTIAL FOR
A FROST/FREEZE EVENT FOR MUCH OF SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA. HIGH PRES CENTERED OVER THE LOWER MISSISSIPPI
VALLEY WILL BUILD E OVERNIGHT. MODELS SHOW OUR PRES GRADIENT
RELAXING AFTER MIDNIGHT AS THE CENTER OF THE HIGH APPROACHES. 18Z
GUIDANCE REMAINS IN GOOD AGREEMENT WITH OUR CURRENT FORECAST
LOW TEMPERATURES. CIRRUS STREAMING E ALONG THE GULF COAST INTO OUR
FAR SOUTHERN GEORGIA ZONES MAY BE A MINOR PLAYER IN SOME MINIMUM
TEMPERATURES ACROSS SOUTHEAST GEORGIA. WE HAVE CONTINUED TO LEAN
ON THE COOLER SIDE OF MOS GUIDANCE WHICH INDICATES LOWER TO MID
30S AWAY FROM THE COAST...WHICH INCLUDES FREEZING TEMPERATURES
ACROSS THE FAR INTERIOR PORTIONS OF THE FORECAST AREA. THUS...THE
FREEZE WARNING WILL CONTINUE THERE WITH FROST ADVISORIES
EVERYWHERE ELSE BUT THE GEORGIA COASTAL ZONES.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 AM SUNDAY/...
SATURDAY...HIGH PRESSURE WILL MOVE OVER THE AREA SATURDAY
RESULTING IN A CONTINUATION OF DRY AND UNSEASONABLY COOL WEATHER. LOW-
LEVEL THICKNESSES AND MOS GUIDANCE SUPPORT HIGHS IN THE LWR-MID
60S. CIRRUS WILL BE ON THE INCREASE THROUGHOUT THE DAY AS A
SOUTHERN STREAM SHORT WAVE SKIRTS EAST ALONG THE NORTHERN GULF
COAST BUT SKIES SHOULD BE MOSTLY SUNNY.
SATURDAY NIGHT...A FEW MORE MID/HIGH CLOUDS EXPECTED SATURDAY
NIGHT WITH THE UPPER SHORTWAVE TROUGH AND THIS WILL HELP KEEP
TEMPS A BIT WARMER THAN TONIGHT. LOWS IN THE MID/UPPER 30S INLAND
MAY SUPPORT SOME FROST SO WILL ADD MENTION TO THE
FORECAST...ALTHOUGH ADVISORIES WILL BECOME A MUTE POINT AS LONG
AS THE GROWING SEASON ENDS TONIGHT ACROSS THESE AREAS.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
WE SHOULD SEE A NICE WARM-UP SUNDAY INTO MONDAY AS THE SURFACE HIGH
SHIFTS OFFSHORE AND A WARM ADVECTION SCHEME DEVELOPS. HIGH TEMPS ON
MONDAY WILL BE SLIGHTLY LIMITED BY AN INCREASE IN HIGH CLOUDS BUT WE
SHOULD STILL SEE LOWER 70S IN MOST AREAS. A POTENT UPPER SHORTWAVE
EMBEDDED IN THE NORTHERN STREAM WILL PASS BY TO THE NORTH MONDAY
NIGHT...PUSHING A COLD FRONT THROUGH THE AREA. MOST AREAS WILL
PROBABLY SEE AT LEAST A BRIEF PERIOD OF RAIN SHOWERS...THUS WE HAVE
MAINTAINED CHANCE POPS MONDAY NIGHT. THE FRONT LOOKS TO STALL
SOMEWHERE NEAR THE SC/GA BORDER ON TUESDAY BEFORE LIFTING BACK NORTH
AS A WARM FRONT TUESDAY NIGHT AHEAD OF A POTENT SOUTHERN STREAM
SHORTWAVE. TUESDAY NIGHT THROUGH WEDNESDAY NIGHT LOOK QUITE
UNSETTLED AS A STRONG CLOSED UPPER LOW TRAVERSES THE GULF COAST
REGION AND INTO CENTRAL NC WHILE A STRONG SURFACE LOW DEVELOPS ALONG
THE GA COAST AND MOVES NORTHEAST. WE CONTINUED WITH SOLID CHANCE
POPS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. COLD HIGH PRESSURE WILL
BUILD IN LATE WEEK WITH DRY WEATHER AND BELOW-NORMAL TEMPS.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL DOMINATE THROUGH 06Z AT KCHS AND KSAV.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIGS/VSBYS POSSIBLE MON
NIGHT THROUGH WED.
&&
.MARINE...
W FLOW DOING IT/S TYPICAL JETTING AND SURGING IN COLD AIR ADVECTION
REGIME OFF OF THE GEORGIA COAST THIS EVENING. GRAYS REEF OBSERVATIONS
HAVE BEEN GUSTING AT OR ABOVE 25 KT SINCE SHORTLY AFTER DUSK. WE
ISSUED A SMALL CRAFT ADVISORY FOR OUR WATERS WITHIN 20 NM A WHILE
AGO AND WE NOW HAVE ADVISORIES FOR THE ENTIRE GEORGIA COAST OVERNIGHT.
THE SURGE APPEARS TO BE WEAKER OFF THE SOUTH CAROLINA COAST UNTIL
YOU TRAVEL BEYOND 20 NM. SEAS 2-4 FT WITHIN 20 NM THIS EVENING...
4 TO 6 FT WELL OFF THE GEORGIA COAST IN OUR OUTER WATERS. CONDITIONS
SHOULD BE IMPROVING LATE TONIGHT WITH WINDS AND SEAS DIMINISHING
AS THE SURFACE HIGH TO THE W BUILDS TOWARD THE WATERS.
SATURDAY AND SATURDAY NIGHT...HIGH PRES WILL SLIDE OVER THE AREA
WITH RATHER TRANQUIL MARINE CONDS ANTICIPATED.
SUNDAY THROUGH WEDNESDAY...HIGH PRESSURE WILL MAINTAIN QUIET
MARINE CONDITIONS SUNDAY AND SUNDAY NIGHT BEFORE A SW PRESSURE
GRADIENT TIGHTENS MONDAY AHEAD OF A COLD FRONT. WINDS SHOULD
REMAIN BELOW ADVISORY THRESHOLDS UNTIL MONDAY NIGHT WHEN THE FRONT
DROPS THROUGH THE WATERS. CONSIDERABLE COLD ADVECTION BEHIND THE
FRONT WILL INCREASE N-NE WINDS LATE MONDAY NIGHT INTO TUESDAY WITH
ADVISORIES POSSIBLE FOR THE OFFSHORE GA WATERS DUE TO A
COMBINATION OF FREQUENT 25 KT WIND GUSTS AND 6 FT SEAS.
WINDS AND SEAS WILL INCREASE DRASTICALLY LATE TUESDAY NIGHT INTO
WEDNESDAY AS A GULF LOW PRESSURE SYSTEM MOVES UP THE SOUTHEAST COAST
AND THE GRADIENT REALLY TIGHTENS. AS USUAL...THE EXACT STRENGTH AND
TRACK OF THE LOW WILL HAVE A HUGE IMPACT ON WIND SPEEDS AND WAVE
HEIGHTS OVER OUR WATERS. STUCK PRETTY CLOSE TO PERSISTENCE WITH THIS
PACKAGE...INDICATING SMALL CRAFT ADVISORY CONDITIONS MOST AREAS ON
WEDNESDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...FROST ADVISORY UNTIL 9 AM EST THIS MORNING FOR GAZ099>101-
114>116-118-137-138-140.
FREEZE WARNING UNTIL 9 AM EST THIS MORNING FOR GAZ087-088.
SC...FROST ADVISORY UNTIL 9 AM EST THIS MORNING FOR SCZ047>051.
FREEZE WARNING UNTIL 9 AM EST THIS MORNING FOR SCZ040-042>045.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
AMZ354-374.
&&
$$
